JG S-552 - It shoots! But it doesn't quite score

[RostokMcSpoons]

Blimey, working on this gun after the AR15, the AK-47 and the F2000, I now realise that this "meddling" lark can be hard. 
But it's scrubbed up quite prettily, I think, with the two-tone sprayed over with Halfords Camo Green
 

View attachment 86044

I'm going to paint the mag too, not really a fan of the 'see my balls' aesthetic  

Anyway, apart from the cosmetics, the good news is the darned thing that cost me all of £50 as a boneyard sale does actually shoot!    Yay!

.... mostly.   (Boo!)

I'm tempted to think there's a loose connection or a short somewhere.  This gun is a bit of a nightmare to put together with a lot of places where it can pinch or rub wires, and although I replaced and re-soldered one contact, and couldn't spot any obvious problems, this either shoots or absolutely nothing happens.   In the absence of Mosfets and clever electronics, it must be electrical, yeah?

Now it's the first I've taken this cheeky chappie apart, and re-assembled it, and it's at this point I have a major "Bedroom tech" confession to make.
 

• I've lost parts.  
  
• I haven't fitted all the parts I've got - on purpose cos it was too damn hard
  
• I've got a part left over - by accident
  
• I may have used some of the screws in the wrong places
  

The lost parts are:

• The spring that goes around the barrel (it's big so no idea how it could have gone walkies)
  
• The tiny screw that holds one of the selector switch mounting blocks in place (the internal silver piece, not the big switch on the outside)
  
• One of the screws for the stock - perhaps used elsewhere 
  

The parts I've got left over are:

• A screw (oops)
  
• The tiny springs and plastic bits to make the selector switches 'detent' .  Bloody nightmare to fit 'em.  Gave up for the moment.
  
• This big chunk of metal (with a spring)
  

View attachment 86045

I thought it was a part of the stock, so didn't worry about it too much, but I'm damned if I can figure out where it's supposed to fit!

Any SG552 experts out there that can tell me where that goes? 

Edit:  Oops again... looking at the box I used to keep the parts in, there's this mystery object too:
View attachment 86052

It might be part of one of my spare trigger assemblies that I used to scavenge the replacement contact from... or it might be some crucial component ?

 

[Adolf Hamster]

That has scrubbed up nicely, the only thing i'd be worried about is as it wears in the 2-tone might still show up underneath, which might spoil an otherwise nice looking pew.

The lost parts thing, well it happens. Part of why keeping a hold of random odd spares is worth doing because you never know when the differential bushing of an hpi baja will find a new home as a spacer for a mainspring in an airsoft pew.....

Not fitting parts because they're a pain is something i've done plenty, you do a "barebones" rebuild to make sure the important stuff is working right then when your sure its all good you can go to the effort of installing the awkward and annoying bits that dont really do much important. Sadly i dont know sigs well enough to help with where the current missing peices should be going.

Wiring wise it does sound like theres an iffy connection somewhere, did you split the box? Could possibly be carboned up contacts?

 

[RostokMcSpoons]

That has scrubbed up nicely, the only thing i'd be worried about is as it wears in the 2-tone might still show up underneath, which might spoil an otherwise nice looking pew.

The lost parts thing, well it happens. Part of why keeping a hold of random odd spares is worth doing because you never know when the differential bushing of an hpi baja will find a new home as a spacer for a mainspring in an airsoft pew.....

Not fitting parts because they're a pain is something i've done plenty, you do a "barebones" rebuild to make sure the important stuff is working right then when your sure its all good you can go to the effort of installing the awkward and annoying bits that dont really do much important. Sadly i dont know sigs well enough to help with where the current missing peices should be going.

Wiring wise it does sound like theres an iffy connection somewhere, did you split the box? Could possibly be carboned up contacts?

I'm not tooooo worried about paint showing through, a quick squirt from the rattle can and it'll be fixed.  I've actually got a couple of new cans on the way, MTN 94 sand colour and a light-ish green, so I might do some camo patterning on the top anyway, in which case a bit of bright green won't really be noticeable.

I got a screw for the detent and also a tiny spring (as bizarrely I can't get either of the ones frpm the gun to fit in one of the switches - it has a smaller hole)
So I'm just short of the barrel spring.  Hopefully I can source that from somewhere... as it's bigger a bit of main spring might even work. 
 

The electrics ... it's not the trigger contacts.   This gun looks very, very lightly used.  The inside of the gearbox still has clean white grease inside.  I'll start re-wiring it by replacing the battery connectors, take the fuse out of the loop too (the fuse is intact).

The gun was firing on Friday.  When I took it to the site on Saturday, it wouldn't. Cheeky lil' bugger.    It might be beyond me to fix it, but at the price I paid I think I can still 'boneyard' it on and get most / all of my money back.  Nowhere near doing that yet though!

 

[Adolf Hamster]

I'm not tooooo worried about paint showing through, a quick squirt from the rattle can and it'll be fixed.  I've actually got a couple of new cans on the way, MTN 94 sand colour and a light-ish green, so I might do some camo patterning on the top anyway, in which case a bit of bright green won't really be noticeable.

I was thinking more that letting that green wear in, get scuffed up etc to show black underneath would look quite good, if the 2-tone wasnt showing.

got a screw for the detent and also a tiny spring (as bizarrely I can't get either of the ones frpm the gun to fit in one of the switches - it has a smaller hole)
So I'm just short of the barrel spring.  Hopefully I can source that from somewhere... as it's bigger a bit of main spring might even work

Motor springs can work sometimes (assuming that's long enough) and smaller diameter than a mainspring.

The electrics ... it's not the trigger contacts.   This gun looks very, very lightly used.  The inside of the gearbox still has clean white grease inside.  I'll start re-wiring it by replacing the battery connectors, take the fuse out of the loop too (the fuse is intact).

The carboning can happen surprisingly quickly, remember working on an ak that looked immaculate save for the carboned contacts.

Can be hard to track down, tbh if it were me i'd be re-wiring it, but then if it were me that'd happen for a mosfet regardless of the state of functionality of the original setup.

 

[Dodgyback]

If you've had enough and you fancy Boneyard selling it on cheap giz a shout bud.

 

[RostokMcSpoons]

If you've had enough and you fancy Boneyard selling it on cheap giz a shout bud.

Cheers, will do - if changing the wiring doesn't do the trick  (I think it will) 

 

[RostokMcSpoons]

Finally got around to tearing the gun down again, now my wire and heatshrink has been delivered... I can see the gun is cocked - is there any way to release the spring tension before I crack the gearbox open?   (I'm off to the pub shortly, so it's a job for tomorrow)

 

[Adolf Hamster]

Finally got around to tearing the gun down again, now my wire and heatshrink has been delivered... I can see the gun is cocked - is there any way to release the spring tension before I crack the gearbox open?   (I'm off to the pub shortly, so it's a job for tomorrow)

couple of options.

with the motor removed probably the least damaging is to have a (flat ended) rod (eg a hex driver) up through the nozzle, push backwards to complete the cycle then gently release

other option is to pull the arl out of engagement, although it depends on the box how easy that can be (some have a cutout for this exact purpose)

 

[RostokMcSpoons]

I went a bit "medieval" on it, jammed the motor up into position and fired a single shot, which did the trick.
I started re-wiring from the battery connector backwards, so did that first.  Then out came the (intact) fuse - success!!  So it seems there was a flaky connection at one end of the fuse causing the main problem.

I've removed the fuse altogether and soldered the wires together, all working nicely.  Now the problem I have is that the motor sounds like it's got half a bag of nails in there, and it's rotating slow as molasses.  I might put the whole thing back together just to see if it'll feed and shoot half decently, before spending more time and money on it.

Good shout on using a motor spring on the barrel

The big mystery piece was indeed from the stock, the shaped prong sticks out from the stock into the body of the gun, when it's in place.

It'll need a Mosfet as one of my new 11.1v batteries fits perfectly in the hand guard.  Any recommendation for a cheapo 'protect the trigger' option? 
I'm thinking the Gate Pico will do ... https://www.patrolbase.co.uk/gate-picossr-3-aeg-micro-mosfet-unit

Where can I buy a mid-length motor?   I've found a couple at Fire Support but £41 is a bit steep.   Any good places to buy a Chinese special at a lower price?

Edit:

Well, well, well.  Put it all back together, got some test shots through it on the 8.4v mini, but for some longer range shots into the garden, I stuck the 11.1v on it.
Cue reasonable rate of fire (13.5rps) and a pleasing 'laser beam' stream of BB's hitting the centre of my backstop.  290-295fps with 0.28g bb's, with some hop applied (I think that's bang on the joule limit)

It's not perfect, it's finicky about the mag position as I had some failures to feed, but damn, even with a possibly knackered motor it feels like there's a good gun in the making

 

 

[Adolf Hamster]

Mosfet wise for cheep and cheerful i tend to go with the nanoasr, that way its a plug and play swap if you ever want to put something like a warfet on.

Not sure motor wise, never really dealt with mid-length aside from accidentally ordering a lonex mid length from gunfire (back when you could order from them)

 

[colinjallen]

I went a bit "medieval" on it, jammed the motor up into position and fired a single shot, which did the trick.
I started re-wiring from the battery connector backwards, so did that first.  Then out came the (intact) fuse - success!!  So it seems there was a flaky connection at one end of the fuse causing the main problem.

I've removed the fuse altogether and soldered the wires together, all working nicely.  Now the problem I have is that the motor sounds like it's got half a bag of nails in there, and it's rotating slow as molasses.  I might put the whole thing back together just to see if it'll feed and shoot half decently, before spending more time and money on it.

Good shout on using a motor spring on the barrel

The big mystery piece was indeed from the stock, the shaped prong sticks out from the stock into the body of the gun, when it's in place.

It'll need a Mosfet as one of my new 11.1v batteries fits perfectly in the hand guard.  Any recommendation for a cheapo 'protect the trigger' option? 
I'm thinking the Gate Pico will do ... https://www.patrolbase.co.uk/gate-picossr-3-aeg-micro-mosfet-unit

Where can I buy a mid-length motor?   I've found a couple at Fire Support but £41 is a bit steep.   Any good places to buy a Chinese special at a lower price?

Edit:

Well, well, well.  Put it all back together, got some test shots through it on the 8.4v mini, but for some longer range shots into the garden, I stuck the 11.1v on it.
Cue reasonable rate of fire (13.5rps) and a pleasing 'laser beam' stream of BB's hitting the centre of my backstop.  290-295fps with 0.28g bb's, with some hop applied (I think that's bang on the joule limit)

It's not perfect, it's finicky about the mag position as I had some failures to feed, but damn, even with a possibly knackered motor it feels like there's a good gun in the making

 

I would not recommend a Gate Pico SSR at the moment; I have had two or three fail in the last few months and am aware of others who have had issues with them.  The Nano mosfets seem ok though.

 

[Asomodai]

Airsoft AEG Motor Systema Medium length NR | eBay

@RostokMcSpoons

Its not a neo motor, but one of the better Ferrite ones that will likely go cheap/ 

 

[RostokMcSpoons]

Yeah, thanks, I saw that a few days ago, already put a low-ish offer in and had it rejected ?
I'll wait to the last moment and snipe it, and if that doesn't work there's another motor going at ~£30 that I can pick up (Matrix 3000, no idea whether they're any good)

And if all that fails, well tbh I don't mind too much.  I found I can pick up an ICS at £41 from Action Hobbies, which is here in MK. 

 

[RostokMcSpoons]

So I won that motor, got it for a fiver.   What a bargain!
Which is kinda handy as I think I've killed it   And a battery (probably).

View attachment 87466

I ran the motor outside the gun and it whizzed away like a good 'un on the little 11.1v battery.  Put it into the pistol grip, and silence, along with whisps of smoke from the battery.  Damn it.  
Not sure if the motor (which is the right length) was just jammed in in such a way that it couldn't turn, or whatever, but the motor is dead.  I connected up the old one, and plugged in a NimH and that still works, so the wiring is ok.

Bah.   And indeed Humbug.
 

 

[ak2m4]

@RostokMcSpoons Does the fried motor still work outside the gun?  Did you have the wires connected the right way?  Couple of things to check just in case.  Some motors don't like certain FETs as well

 

[RostokMcSpoons]

Hi @ak2m4
No the motor doesn't work at all now.   I've tried turning the axle manually just to make sure it's not a temporary internal jam.  It turns (it's quite hard to move, decent magnets?)

The red was connected to the red dotted tab, I double checked before pulling the trigger.

No MOSFET installed (nor a fuse - perhaps unfortunately)

(Amazingly the battery seems to have survived - the plug in tester is reporting voltages on all 3 cells)

 

[ak2m4]

does indeed sound like it's failed, you can check the brushes and springs etc.  hard to move doesn't always mean decent magnets, poor motor shimming or broken bearings can cause that as well